The present invention relates to a generating apparatus for charging the battery of an automobile engine, and more particularly to a generating apparatus with an adjustable speed change mechanism which enables the charging generator to be run at a varying speed with respect to the rotational speed of the engine.
In a typical automobile engine, a charging generator is belt-driven by a drive pulley mounted on the crankshaft of the engine. The input shaft of the charging generator has a pulley mounted thereon which is drivingly connected to the drive pulley by a belt. The pulley ratio of the drive pulley and the pulley mounted on the input shaft of the charging generator is constant, and is generally set so that the rotational speed of the charging generator is 2-3 times the rotational speed of the drive pulley. By so setting the pulley ratio, the charging generator can produce adequate electrical power even when the engine is rotating at a low speed, such as when it is idling.
However, when the engine is operating at high speeds, the rotational speed of the charging generator is still 2-3 times that of the drive pulley, and at high rotational speeds, the output produced by the charging generator reaches a point of saturation. Namely, in high speed ranges, an increase in input power to the charging generator produces almost no increase in the electrical output power, which means that the efficiency of the charging generator becomes very low at high speeds. This reduction in generating efficiency decreases the fuel efficiency of the engine as a whole and is thus undesirable.